Molded flare assembly

ABSTRACT

A fully formed flared portion is molded as part of the main body of the one embodiment of the fitting. The flared portion is inserted through the back side of a retaining cap. A collet assembly is assembled together around the smallest diameter of the tube fitting below the flare. The collet assembly is fitted into the top of a mating nut. The retaining cap is then snapped onto the top of the nut, completing the assembly.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from provisional application60/305,002, filed Jul. 12, 2001, the entire disclosure of which isincorporated herein by this reference, and from application Ser. No.10/193,362, filed Jul. 11, 2002 the entire disclosure of which isincorporated herein by this reference.

BACKGROUND OF THE DISCLOSURE

A typical type of flared plastic fitting used for fluid flowapplications has a flared tube end with a mating nut positioned inboardof the flared end to couple to a corresponding flared fitting.Conventional plastic flared fittings, such as a right angle fitting, arefabricated by molding a straight tube extension as part of the main bodyof the fitting. The tube extension is heated to a softened state, whichcan typically take two to three minutes. The tube extension is theninserted through the back side of the mating nut, pushed onto a formingmandrel and allowed to cool. After cooling, which may take on the orderof five minutes to as much as ten to twelve minutes for some processes,the mandrel is removed from the now formed flared end.

This technique for forming a flared fitting has several disadvantages.Hot flaring molded fittings is a time consuming and inefficient process,requiring skilled technicians with special tools and equipment. Even so,the process has a typical reject rate on the order of 10% to 30%.Another disadvantage is that hand forming the flare results in lack ofprecision in the finished part. The trueness of the flared end withrespect to the nominal tube fitting axis suffers due to the handforming. The resulting parts are low tolerance, and this can result in abuildup of tolerances when many fittings are employed in aninstallation.

The hot flaring technique has also been implemented in semi-automatedand automated systems, yet parts fabricated using semi-automated orfully automated systems have been found to have problems of lack oftrueness and low tolerances.

It would be advantageous to provide a flare fitting with highertolerance than afforded by known techniques.

It would also be advantageous to provide a technique for forming flaredfittings resulting in higher throughput and which requires less skillthan known hand forming techniques.

SUMMARY OF THE DISCLOSURE

In an exemplary technique in accordance with an aspect of thisinvention, a fully formed flare is molded as part of the main body ofthe fitting. The flared portion is inserted through the back side of aretaining cap. A collet assembly is assembled together around thesmallest diameter of the tube fitting below the flare. The colletassembly is fitted into the top of the mating nut. The retaining cap isthen snapped onto the top of the nut, completing the assembly.

Fully molded flared fitting bodies are molded in a finished state,providing dimensions that are accurate and repeatable. Assembly issimple.

BRIEF DESCRIPTION OF THE DRAWING

These and other features and advantages of the present invention willbecome more apparent from the following detailed description of anexemplary embodiment thereof, as illustrated in the accompanyingdrawings, in which:

FIG. 1 is an exploded cross-sectional view of a molded flared rightangle fitting in accordance with aspects of the invention.

FIG. 2 is a view similar to FIG. 1, but showing the collet piecesassembled into a collet assembly.

FIG. 3 is a cross-sectional view of the fully assembled flared fitting.

FIGS. 4-6 illustrate the flared fitting of FIGS. 1-3 in various stagesof assembly.

FIG. 4 is a longitudinal cross-sectional view of the fitting with thecollet pieces assembled into a collet assembly, without the threadednut. FIG. 4A is a top view of the fitting as shown in FIG. 4.

FIG. 5 is a side view of the fitting of the fitting with the colletpieces assembled into a collet assembly, showing how the collet piecesare fitted together to form the collet assembly. FIG. 5A is a top viewof the collet pieces in exploded view. FIG. 5B is a side view of thecollet pieces in exploded view.

FIG. 6 is a cross-sectional view of the flared fitting with the nutshown positioned for assembly in phantom, and in assembled form.

FIG. 7 illustrates the flared fitting engaged with a mating connector.

DETAILED DESCRIPTION OF THE DISCLOSURE

FIGS. 1-6 illustrate an exemplary embodiment of a right angle flaredfitting 20 in accordance with aspects of the invention. The fitting 20is a right angle fitting comprising a fully molded flare body 20,injection molded from a material such as perfluoroalkoxy (PFA), or othermelt-processable fluoropolymers or melt-processable polymers such aspolypropylene. The body part 30 is fully formed in the molding process,wherein a male end 32 is formed having an inner diameter D1 and an outerdiameter D2, and a threaded outer peripheral portion 33. A right angleis defined between the male end and the flared female end 36. End 36 hasan outer diameter D3 at portion 34, and is flared to form female flaredend 36 having a maximum outer diameter D4. Portion 34 has a smallerouter diameter D3 than dimension D4 or dimension D5 at the right angleportion 35, thus defining a shoulder 38 on the molded body part 30.

The fitting 20 further includes a retaining cap 40, a collet assemblyformed of a plurality of collet pieces, in this example two colletpieces 52, 54 (FIG. 2), and an expandable nut 60. These elements can befabricated from a rigid plastic material such as polyvinylildenefluoride (PVDF), ethylene tetrafluoroethylene (ETFE), or for someapplications, the same material as that of the body member 30, in thisexemplary embodiment PFA. Each of these elements are typically injectionmolded, fully formed parts.

The nut 60 has a plurality of slightly tapered slots 62 formed in end64, in this exemplary embodiment wherein the nut is fabricated of PVDF,six slots, each having a slot width of 0.028 inch at the end 64 and awidth of 0.025 inch at the end distal from the nut end 64. As a resultof the slots 62, the nut at end 64 is expandable. For other materials,such as PFA, the slots may be wider. The slots are formed wide enough toreceive the locking tabs on the collet assembly. The external peripheryof the nut adjacent the end 64 has a compound angle shape, with acircumferential line 66 of reduced diameter inward of the end. Surface66A leads from the end 64 back to the line 66, and surface 66B leadsfrom line 66 away from the end. The size of the angles defined bysurfaces 66A and 66B will depend on the application and the materialsused in fabrication of the parts. The interior surface of the nut at end64 is beveled, to form a chamfer surface 65, to facilitate insertion ofthe collet assembly 50.

The retaining cap 40 has a back surface 42 and a central opening 44formed therein of a diameter large enough to pass the flared end 36 ofthe body portion therethrough. The inner surface has a shape which iscomplimentary to the shape of the outer periphery of the nut 60 adjacentend 64. Thus, circumferential line 46 defines a reduced diameter equalto the diameter of line 66 on the nut 60, with angled cap surfaces 46Aand 46B matching the angled nut surfaces 66A and 66B.

FIG. 3 shows the fitting 20 in fully assembled form. The female end 36is adapted to connect to a compatible fitting having a male end similarto end 32, with the nut 60 engaging a threaded peripheral portion of thecompatible fitting to draw the flared female end and the male end (notshown in FIG. 3) tightly together. The cap 40 is interference fittedover the end 64 of the nut, with the complimentary inner shape (definedby 46, 46A, 46B) of the cap engaging against the outer shape (defined by66, 66A, 66B) of the nut.

FIGS. 4-6 illustrate an exemplary assembly technique in accordance withan aspect of the invention. After the body part 30 has been fabricatedin a molding process such as injection molding, the flared portion 36 isinserted through opening 42 and the back side of the retaining cap 40.The cap 40 is positioned below the shoulder 38 of the body 30, asillustrated in FIG. 4.

Referring now to FIG. 5, the collet pieces 52, 54 are assembled togetheraround the smallest diameter (D3) region 34 of the tube fitting belowthe flare 36 to form the collet assembly 50. Each collet piece has a pin(52A, 54A) which fits into a corresponding hole formed in the otherpiece. Each collet piece also has a locking tab (52B, 54B) whichprotrudes from an outer peripheral surface of the piece. The tabs 52B,54B have a width sized to slide into a slot 62 in the nut 60; the tabwidth in this exemplary embodiment, wherein the collet pieces arefabricated of PVDF, is 0.020 inch. The tab width for an embodimentfabricated of PFA could be wider. The tabs and the slots in the nut willhave roughly the same width; the slots are slightly wider to providesome clearance, say on the order of 0.004 inch in one exemplaryembodiment. The foregoing dimensions are by way of example only; forparticular applications wider or narrower slots and tabs couldalternatively be employed. The tabs 52B, 54B are aligned withcorresponding ones of the slots 62 in the locking nut, and the colletassembly is pushed into the end 64 of the nut. The slots 62 have a depthselected to allow the collet assembly to be fitted into the end 64 ofthe nut so that the collet assembly does not protrude from the nut end64. The collet pieces 52, 54 have beveled surfaces 52C, 54C which abutshoulder surfaces 52D, 54D. The beveled surfaces 52C, 54C essentiallymatch the chamfer surface 65 of the nut opening at end 64, and as thecollet assembly is pressed into the end of nut 60, the nut end willexpand slightly to allow the leading end 56 (FIG. 5) of the assembly 50to enter the nut opening at end 64, with the chamfer surface 65facilitating the insertion of the collet assembly. As the colletassembly is pressed upwardly into the end of the nut, beveled surfaces52C, 54C will come into contact with the chamfer surface 65 of the nut,and the nut end can resume its normal diameter. The shoulder surfaces52D, 54D of the collet assembly engage against the shoulder surface 67of the nut, preventing the collet assembly from sliding out the end 64of the nut. The tabs prevent the collet assembly from being pressedthrough the nut completely, stopped by the ends of the slots.

Next, again referring to FIG. 6, the retaining cap 40 is press fittedonto the end 64 of the nut 60. The cap 40 has a beveled interior surfaceat 46, and this surface provides an interference fit of the cap onto thenut, locking the cap in place. The fully assembly fitting 20 isillustrated in FIG. 3. The nut 60 assembled with the collet assembly 50and cap 40 is rotatable about the flared end 36 of the body 30, toengage a threaded male portion of a mating connector end. FIG. 7illustrates the fitting 20 engaged with a mating connector 100 having amale end 104 which is received withing the flared end 36 of the fitting20. The threads of the nut 60 engage a threaded outer periphery 102 ofthe connector 100 to draw the male end tightly into the flared end andcreate a fluid tight connection.

The assembly fitting 20 has several advantages. One is that, because thebody 30 including the flared portion 36 is fully molded, the body hasrelatively high precision. There is a much smaller dimensional variationin the flared portion, than in parts fabricated using a conventional hotflare technique. This can provide greater surface area engagement withmating parts, reducing risk of leakage and improved reliability of theconnection with mating parts in an installation. Further, the fitting iseasy to assemble, and there is little waste.

While the molded flare fitting has been illustrated with respect to aright angle fitting, the technique can be used on other types of flarefittings, such as sweep elbow fittings, T connectors and straightconnectors. Exemplary fitting sizes include ¼ inch, ⅜ inch, ½ inch, ¾inch, 1 inch and 1¼ sizes, where the dimensions are of the dimension D1(FIG. 1). Other sizes can also be employed.

It is understood that the above-described embodiments are merelyillustrative of the possible specific embodiments which may representprinciples of the present invention. Other arrangements may readily bedevised in accordance with these principles by those skilled in the artwithout departing from the scope and spirit of the invention.

1. A method for assembling a molded flare assembly, comprising:injection molding a body structure having a fluid passageway formedtherethrough and a fully formed flared portion at a first end, the bodyportion having a small diameter portion adjacent the flared portion;fitting a retainer cap structure over the flared portion and to thesmall diameter portion; fitting a collet structure onto the smalldiameter portion of the body structure such that the cap structure isinward of the flared portion and the collet structure; positioning anend of a mating nut structure having an opening formed therethroughadjacent the flared portion; and press fitting the nut structure and thecollet structure together such that the collet structure is receivedwithin said nut end in a non-rotatable relationship with said nutstructure, and wherein said nut structure, said collet structure andsaid retainer cap structure are rotatable about said body structure. 2.The method of claim 1, further comprising: press fitting the retainercap over the end of the nut structure to retain the collet structure insaid nut end.
 3. The method of claim 1, wherein said main body structureis fabricated of a melt-processable fluoropolymer.
 4. The method ofclaim 1, wherein said collet pieces are fabricated of a rigid plasticmaterial.
 5. The method of claim 4, wherein said rigid plastic materialis polyvinylildene fluoride (PVDF), ethylene tetrafluoroethylene (ETFE),or perfluoroalkoxy (PFA).
 6. The method of claim 3, wherein said colletpieces are fabricated of said melt-processable fluoropolymer.
 7. Themethod of claim 6 wherein said melt-processable fluoropolymer isperfluoroalkoxy (PFA).
 8. The method of claim 1, wherein said main bodystructure is fabricated of perfluoroalkoxy (PFA).
 9. A method forassembling a molded flare assembly, comprising: injection molding a bodystructure having a fluid passageway formed therethrough and a fullyformed flared portion at a first end, the body portion having a smalldiameter portion adjacent the flared portion; assembling a multi-piececollet structure onto the small diameter portion of the body structure,wherein the collet structure has a plurality of protruding tabs;positioning an end of a mating nut structure having an opening formedtherethrough adjacent the flared portion, the nut structure having aplurality of slots formed therein from said end to a slot depth to allowsome expansion of the nut end; aligning the collet tabs withcorresponding slots in the nut structure; and press fitting the nutstructure and the collet assembly together such that the collet assemblyis received within said nut end and the collet tabs fit into thecorresponding slots.